The invention relates to a-sterilizing container for holding surgical instruments or other sterilizing material during sterilization and for maintaining the sterilized condition during storage and transportation. During sterilization, such sterilizing containers must permit exchange of media inside the sterilizer.
In order to permit exchange of media, it is known to equip the sterilizing containers with double valves which, during the sterilizing process in the sterilizer, alternately open and close depending on the pressure difference, and which, after the sterilizing process, remain closed in order to protect the sterilized material from penetration of microorganisms during storage. Such sterilizing containers are known, for example, from DE-B 1,217,550, DE-B 1,217,551 and DE Patent 1,642,161 and DE Patent 3,202,430. Other known sterilizing containers have container openings which are equipped with a filter through which the exchange of media takes place during the sterilizing process in the sterilizer, and which, after completion of the sterilizing process, are intended to form a barrier to penetration of microorganisms during storage of the sterilizing container. Such sterilizing containers are known, for example, from DE 3,438,463 C2. From this patent specification, it is also known to mount a filter leaf and a spring-preloaded filter holder plate in such a way that when a predetermined pressure difference is exceeded, the filter leaf can be lifted up like a valve from the cover openings, thus establishing a secondary flow route. A bypass is thus created as soon as the external pressure becomes so high that there is a danger of the container being squeezed together.
Such an overpressure valve is also proposed in DE 4,125,673 C1. This overpressure valve, which opens toward the inside of the container when a predetermined external pressure is established, can be pushed into a guide on the container wall. A filter assigned to a further container opening can be pushed into a similar guide.
This valve/filter combination known from DE 4,125,673 C1 and other valve/filter combinations are intended only as protective means for preventing the container from being squeezed together.
In sterilizing containers equipped with filters, the exchange of media in the sterilizer was intended to take place through these filters. The filters were accordingly designed in such a way that they could compensate sufficiently quickly for the pressure differences which occurred. This entailed a corresponding pore size which, although small enough to protect the container contents from dust and large-volume microorganisms, was unable to guarantee that no microorganisms could get in, particularly extremely small viruses or fungal spores. Thus, in the sterilizing containers equipped with filters, there was, over the course of time, an increasing risk of penetration of microorganisms.
The invention is therefore based on the object of making available a sterilizing container equipped with filters, in which the filter has fine pores and is designed in such a way that there is no penetration of microorganisms after sterilization, even after long storage periods, but in which the short-term pressure differences occurring in modern autoclaves can be reduced without damage to filter or container.
Thus, according to the invention, in addition to the filter, inlet and outlet valves are provided which are also intended to act during the sterilizing process and do not serve merely as safety valves, and which come into action as soon as the pressure difference from outside to inside or from inside to outside has become so great that the exchange of media through the filter material cannot take place sufficiently quickly.
Accordingly, the invention is based on the knowledge that sterilizing containers can be equipped with filters of any desired fineness if care is taken to ensure that a bypass is created in both directions, i.e. not only from outside to inside, but also from inside to outside, when a pressure difference predetermined by the structure is exceeded.
According to a preferred embodiment of the invention, filter and valves are arranged in a common container opening, for example in an opening of an intermediate cover, provided with a protective cover, or in a container wall or in the bottom. A particularly expedient and robust construction is obtained if the filter is clamped immovably in a holding frame and at least one of the valves is integrated in the holding frame, which in turn is braced firmly on the opening edge. For the invention, however, the possibility should be left open to arrange the filter and at least one of the valves in different container openings, which can be expedient, for example, if a condensate bleeder valve is to be arranged on the bottom of the sterilizing container. This condensate bleeder valve can then be designed at the same time as an overpressure valve, via which an increased internal pressure in the container can be reduced.
The two valves can be integrated in the holding frame of the filter in such a way that there are no outwardly movable parts which could come into contact with the container contents and which could be manipulated from outside.
According to the invention, the filter material can have almost any desired flow resistance, and it cannot slip, thus ruling out the danger of an open bypass remaining after completion of the sterilizing process.
Compared to the known spring-mounted filter holder plates in which the filter is opened during occurrence of the bypass flow and, on account of the flow, can slip into another position or become stuck, the filter in the arrangement according to the invention always provides correct sealing. According to the invention, the whole arrangement (bypass with filter) is immovable, which results in a dual safety advantage:
a) the function of the bypass cannot be blocked by the container contents;
b) the bypass cannot be inadvertently actuated by the container contents or from outside.
According to the invention, all known filter materials can be used, for example surface filters made of paper, synthetics or textile, and also membrane filters or 3D volume filters and submicron particulate filters, by which even viruses or fungal spores can be held back.
Preferred designs of the filter/valve combination are set out in the dependent claims and in the description of illustrative embodiments.